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1. Maculinea (= Phengaris ) species of butterfly have complex life‐styles in which the larvae feed briefly on specific foodplants before entering the final instar, after which they live as social parasites within Myrmica ant colonies and acquire 98–99% of their ultimate biomass by either preying on ant brood (predatory species) or being fed by worker ants (cuckoo species). Cuckoo species demonstrate two growth forms, whereby some individuals develop to pupate in 11 months and others remain 23 months in the nest, a strategy that in theory represents the most efficient exploitation of resources within Myrmica societies. Early studies suggested that development rates in Maculinea rebeli (referred to by other authors as the xerophilous form of Maculinea alcon ) were not plastic but represented an unusual fixed polymorphism, in which eggs were genetically predetermined as 1‐ or 2‐year larvae. 2. We tested this idea in lab experiments using M. rebeli from the French Hautes‐Alpes, with these results: (i) the growth strategy of every individual larva is pre‐determined by the mother either genetically or, less probably, during oogenesis. (ii) Intra‐nest competition and host fitness affects survival and growth but does not influence the inherent growth strategy. (iii) The ratio of 1‐ and 2‐year developing larvae is initially about 50:50, although differential survival in crowded nests may alter the ratio of surviving individuals. (iv) All females tested laid eggs that hatched into both 1‐ or 2‐year developers. (v) Growth patterns vary between different regions. Larvae from the Spanish Pyrenees initially grow less than those from the Alps, with a smaller initial differentiation between the size classes.

In natural ecosystems, relationships between organisms are often characterised by high levels of complexity, where vulnerabilities in multi-trophic systems are difficult to identify, yet variation in specific community modules can be traceable. Within the complex community interactions, we can shed new light on dynamics by which co-evolutionary outcomes can inform science-led conservation. Here we assessed host-ant use in six populations of the butterfly Phengaris (=Maculinea) rebeli, an obligate social parasite of Myrmica ants and a model system in evolutionary and conservation ecology. Starting from the initial distribution of eggs, we estimated the survival of the parasite in the wild in nests of seven Myrmica ant species, and analysed the chemical cues evolved by the parasites to subvert its host defences. We found local variations in host specificity that are consistent with similarities found in the chemical profiles of hosts and parasites on different sites. At some sites, only one ant species is successfully exploited; at others, multiple-host populations are used. Understanding how stable or adaptable these associations are is essential knowledge when devising conservation measures to maintain keystone species of ant and locally adapted populations of Phengaris butterfly species, which are rare, threatened and a high priority for conservation worldwide.

A cornerstone of conservation is the designation and management of protected areas (PAs): locations often under conservation management containing species of conservation concern, where some development and other detrimental influences are prevented or mitigated. However, the value of PAs for conserving biodiversity in the long term has been questioned given that species are changing their distributions in response to climatic change. There is a concern that PAs may become climatically unsuitable for those species that they were designated to protect, and may not be located appropriately to receive newly-colonizing species for which the climate is improving. In the present study, we analyze fine-scale distribution data from detailed resurveys of seven butterfly and 11 bird species in Great Britain aiming to examine any effect of PA designation in preventing extinctions and promoting colonizations. We found a positive effect of PA designation on species' persistence at trailing-edge warm range margins, although with a decreased magnitude at higher latitudes and altitudes. In addition, colonizations by range expanding species were more likely to occur on PAs even after altitude and latitude were taken into account. PAs will therefore remain an important strategy for conservation. The potential for PA management to mitigate the effects of climatic change for retracting species deserves further investigation.

The dramatic recovery of three species of grassland specialist butterfly threatened with extinction at their high latitude range limits in the 1980s has been attributed to two factors: increased grazing on calcareous grassland sites and warmer air temperatures. Both result in the warming of soil surface temperatures, favourable to the larvae of these species. We address the influence of both of these factors on the habitat usage of the butterfly Polyommatus bellargus, undergoing recovery at its northern range edge. We test the hypothesis that the larval niche of P. bellargus has become less constrained in the past three decades, whilst controlling for changes in habitat structure. Once habitat change has been accounted for we find no evidence for a broadening of the larval niche of P. bellargus. Further, we show that coincident with the recovery of P. bellargus there have been drastic reductions in average turf height across UK chalk grasslands, but changes in air temperature have been highly variable. We conclude that changes to soil surface temperatures caused by reducing turf heights will have been a more consistent influence than air temperature increases, and so habitat improvements through increased grazing will have been the major driver of recovery in P. bellargus. We consider the need to account for changes in habitat when exploring the impacts of recent climate change on local habitats in thermophilous species, and emphasise the continued importance of habitat management to support such species under variable local climates.

Lepidoptera are one of the four major insect orders, and one of the best studied invertebrate groups, containing over 160,000 described species and an estimated equal number of undescribed species, arranged in 124 families (Kristensen et al. 2007). Lepidoptera occupy all except the very coldest terrestrial regions, but the Neotropics and Indoaustralian region have five times more species per unit area than the Palaearctic and Nearctic, and three times more than the Afrotropical region (Heppner 1991). They are scale-winged insects, traditionally divided into three major assemblages: micro-moths, butterflies and macro-moths (Kristensen et al. 2007). The order represents a mega-diverse radiation of almost exclusively phytophagous insects, probably correlated with the great diversification of flowering plants since the Cretaceous (Menken et al. 2010). They provide many vital and economically important services within terrestrial ecosystems (e.g. nutrient recycling, soil formation, food resources and pollination). The scale of these contributions is illustrated by the estimate that blue tit (Parus caeruleus) chicks consume at least 35 billion caterpillars each year in the UK alone (Fox et al. 2006). Lepidoptera also have considerable human significance, both economic and scientific. A growing industry farms pupae for supply to butterfly houses across the world. One moth species has been domesticated in order to provide silk (i.e. Bombyx mori

International audience; Caterpillars of the butterfly Maculinea rebeli develop as parasites inside ant colonies. In intensively studied French populations, about 25% of caterpillars mature within 1 year (fast‐developing larvae [FDL]) and the others after 2 years (slow‐developing larvae [SDL]); all available evidence indicates that this ratio is under the control of egg‐laying females. We present an analytical model to predict the evolutionarily stable fraction of FDL (pESS). The model accounts for added winter mortality of SDL, general and kin competition among caterpillars, a competitive advantage of SDL over newly entering FDL (priority effect), and the avoidance of renewed infection of ant nests by butterflies in the coming season (segregation). We come to the following conclusions: (1) all factors listed above can promote the evolution of delayed development; (2) kin competition and segregation stabilize pESS near 0.5; and (3) a priority effect is the only mechanism potentially selecting for . However, given the empirical data, pESS is predicted to fall closer to 0.5 than to the 0.25 that has been observed. In this particular system, bet hedging cannot explain why more than 50% of larvae postpone growth. Presumably, other fitness benefits for SDL, for example, higher fertility or longevity, also contribute to the evolution of delayed development. The model presented here may be of general applicability for systems where maturing individuals compete in small subgroups.

Butterflies are better documented and monitored worldwide than any other nonpest taxon of insects ( 1 ). In the United Kingdom alone, volunteer recorders have sampled more than 750,000 km of repeat transects since 1976, equivalent to walking to the Moon and back counting butterflies ( 2 ). Such programs are revealing regional extinctions and population declines that began before 1900 ( 3 , 4 ). In a recent study, Habel et al. report a similar story based on inventories of butterflies and burnet moths since 1840 in a protected area in Bavaria, Germany ( 5 ). The results reveal severe species losses: Scarce, specialized butterflies have largely disappeared, leaving ecosystems dominated by common generalist ones. Similar trends are seen across Europe ( 6 ) and beyond, with protected areas failing to conserve many species for which they were once famed.

Although grasslands are crucial habitats for European butterflies, large-scale declines in quality and area have devastated many species. Grassland restoration can contribute to the recovery of butterfly populations, although there is a paucity of information on the long-term effects of management. Using eight UK data sets (9-21. years), we investigate changes in restoration success for (1) arable reversion sites, were grassland was established on bare ground using seed mixtures, and (2) grassland enhancement sites, where degraded grasslands are restored by scrub removal followed by the re-instigation of cutting/grazing. We also assessed the importance of individual butterfly traits and ecological characteristics in determining colonisation times. Consistent increases in restoration success over time were seen for arable reversion sites, with the most rapid rates of increase in restoration success seen over the first 10. years. For grasslands enhancement there were no consistent increases in restoration success over time. Butterfly colonisation times were fastest for species with widespread host plants or where host plants established well during restoration. Low mobility butterfly species took longer to colonise. We show that arable reversion is an effective tool for the management of butterfly communities. We suggest that as restoration takes time to achieve, its use as a mitigation tool against future environmental change (i.e. by decreasing isolation in fragmented landscapes) needs to take into account such time lags. © 2012 Elsevier Ltd.

The benefits of protected areas (PAs) for biodiversity have been questioned in the context of climate change because PAs are static, whereas the distributions of species are dynamic. Current PAs may, however, continue to be important if they provide suitable locations for species to colonize at their leading-edge range boundaries, thereby enabling spread into new regions. Here, we present an empirical assessment of the role of PAs as targets for colonization during recent range expansions. Records from intensive surveys revealed that seven bird and butterfly species have colonized PAs 4.2 (median) times more frequently than expected from the availability of PAs in the landscapes colonized. Records of an additional 256 invertebrate species with less-intensive surveys supported these findings and showed that 98% of species are disproportionately associated with PAs in newly colonized parts of their ranges. Although colonizing species favor PAs in general, species vary greatly in their reliance on PAs, reflecting differences in the dependence of individual species on particular habitats and other conditions that are available only in PAs. These findings highlight the importance of current PAs for facilitating range expansions and show that a small subset of the landscape receives a high proportion of colonizations by range-expanding species.

Summary 1. Monitoring the abundance of insect populations is increasingly valuable to understand their population dynamics, plan management strategies and assess the attainment of conservation targets. As monitoring is often constrained in time and space, it is important to have a model of the temporal variation in numbers to enable limited field data to be fitted into a broader framework, and to estimate the total detectable population on a site. We use adult butterflies as a study system, because they are widely monitored, sensitive indicators of environmental change. 2. We derive a generic algebraic expression for the shape of the population curve that describes how the number of adult butterflies observed at a site varies through the flight period. This novel expression contains parameters corresponding to total detectable population, start-date and length of eclosion period, and mean life span. These can be optimised to fit observed series of counts (e.g. butterfly transect data, moth light-trap counts) for individual species, sites and years, using a reliable grid-refinement optimisation procedure. 3. Assumptions about survivorship and death rate are supported by field observations of the life span of two species tested. The modelled population curve (POPFIT) closely fits observed transect data for three further species. 4. We give two simplified methods of estimating the total transect population: from the Index of Abundance and from the peak population. We discuss extrapolation of transect results to estimate total site population, taking account of observed sampling efficiencies. 5. Our new method compares favourably with previous models for assessing patterns of population change at monitored sites and can assist with the planning of optimal monitoring strategies. As well as population estimates, it allows standardised phenological parameters to be derived from field data and provides a standard curve for theoretical studies. The method is applicable to all insect species whose adults have distinct, non-overwintering generations and to all other monitored organisms with similar demographies.

Bringing Back the Large Blue Flagship endangered species, such as the Large Blue butterfly have driven conservation programs worldwide. However, the Large Blue butterfly ( Maculinea arion ) became extinct in the United Kingdom. The apparent driver of this extinction was a complex set of events documented by Thomas et al. (p. 80 , published online 18 June; see the Perspective by Settele and Kühn ). Life-tables and modeling demonstrate how ecological changes, affecting multiple species, cascaded to negatively impact Large Blue populations. When the changes that cause these extinctions were addressed, reintroduction efforts proved successful. Other insects have experienced similar declines and, hopefully, on sites where their known resources remain abundant, a similar approach may be applied.

Ants dominate terrestrial ecosystems through living in complex societies whose organization is maintained via sophisticated communication systems. The role of acoustics in information exchange may be underestimated. We show that Myrmica schencki queens generate distinctive sounds that elicit increased benevolent responses from workers, reinforcing their supreme social status. Although fiercely defended by workers, ant societies are infiltrated by specialist insects that exploit their resources. Sounds produced by pupae and larvae of the parasitic butterfly Maculinea rebeli mimic those of queen ants more closely than those of workers, enabling them to achieve high status within ant societies. We conclude that acoustical mimicry provides another route for infiltration for ∼10,000 species of social parasites that cheat ant societies.

Phenology shifts are the most widely cited examples of the biological impact of climate change, yet there are few assessments of potential effects on the fitness of individual organisms or the persistence of populations. Despite extensive evidence of climate‐driven advances in phenological events over recent decades, comparable patterns across species' geographic ranges have seldom been described. Even fewer studies have quantified concurrent spatial gradients and temporal trends between phenology and climate. Here we analyse a large data set (~129 000 phenology measures) over 37 years across the UK to provide the first phylogenetic comparative analysis of the relative roles of plasticity and local adaptation in generating spatial and temporal patterns in butterfly mean flight dates. Although populations of all species exhibit a plastic response to temperature, with adult emergence dates earlier in warmer years by an average of 6.4 days per °C, among‐population differences are significantly lower on average, at 4.3 days per °C. Emergence dates of most species are more synchronised over their geographic range than is predicted by their relationship between mean flight date and temperature over time, suggesting local adaptation. Biological traits of species only weakly explained the variation in differences between space‐temperature and time‐temperature phenological responses, suggesting that multiple mechanisms may operate to maintain local adaptation. As niche models assume constant relationships between occurrence and environmental conditions across a species' entire range, an important implication of the temperature‐mediated local adaptation detected here is that populations of insects are much more sensitive to future climate changes than current projections suggest.

Mowing influences two endangered butterfly species, Maculinea nausithous and Maculinea teleius, directly through egg destruction and larval mortality on the mown plants and indirectly through altering the abundance of their sequential resources in meadows (Sanguisorba plants for oviposition and early larval development and Myrmica ant nests for later larval development and pupation). Although conservation biologists have argued that mowing during the adult stage is detrimental to population persistence, it is not obvious how the timing and frequency of mowing impact on population dynamics. A simulation model was used to investigate how current 'traditional' mowing regimes could be altered to reconcile butterfly conservation with agriculture. The key mechanism affecting the impact of mowing on population persistence was the interaction between density-independent and density-dependent mortalities in different larval stages of each life cycle. Because of this interaction, optimal mowing regimes for butterfly conservation were sensitive to the type of density regulation displayed by each species, and to landscape attributes such as the influence of climate on resource availability and the level of parasitism. Despite this sensitivity, we were able to identify robust mowing regimes appropriate for a wide range of landscape attributes and to derive general management recommendations. Synthesis and applications. Our results showed that the 'traditional' mowing regime (twice per year with the second cut during the flight period) was always detrimental to the two butterfly species at both local (single population) and regional (metapopulation) scales. However, mowing once a year, or every second or third year, before or after the flight period, was appropriate for both species in the considered landscapes. Maculinea teleius could persist only at a regional scale, assuming dispersal among the meadows, whereas M. nausithous could persist at both local and regional scales. Thus it is essential that the recommended mowing regimes are applied across several connected meadows within reach of dispersing butterflies if both butterflies are to be conserved in a region

We develop a “case model” approach to investigate how conservation measures may affect the ecology of a community module, defined as a small number of tightly interacting species. The community module consists of a parasitic butterfly and its two hosts, a plant and an ant. The butterfly Maculinea alcon and its host plant Gentiana pneumonanthe have long been used as indicators of high-quality Palearctic heath and moist grassland ecosystems, and both species have been targeted for ecological research and specific conservation management. We constructed a mechanistic model of this community module, including dynamics for the three species, and conducted simulation studies of different conservation strategies (burning, sod cutting, mowing, and grazing). We identified several key parameters for the conservation of Maculinea alcon and its host plant as well as the most efficient conservation strategies for their dual long-term persistence. Our results show that the conditions that optimize the size of the butte...

We employ an empirically motivated “case model” approach to investigate the theoretical foundations for the conservation of the endangered butterfly Maculinea arion. Maculinea butterflies have highly specialized larvae that sequentially exploit a plant and an ant species. Our study establishes that M. arion's specialized life cycle, including scramble competition for limiting resources, and the spatially discrete nature of its resources, make it more sensitive to environmental variation and more prone to local extinction than other univoltine phytophagous species. We find that the number and spatial distribution of the butterfly's resources are key factors in their population dynamics, especially for M. arion populations in habitats associated with high larval survival and high adult fecundity. Factors that increase juvenile competition have first a positive effect on adult population size, but beyond a threshold this effect becomes negative. In general, oscillatory dynamics emerge for high potential grow...

We investigated the niche requirements of the summer and autumn/spring generations of the bivoltine butterfly, Polyommatus bellargus Rott., and their implications for population dynamics at sites occurring near its northern range margin. The larvae of this species are sedentary, and the turf height and shelter of Hippocrepis comosa foodplants selected for egg-laying accurately predict larval distributions within United Kingdom (UK) sites. We found a significant shift between the plants used for egg-laying in each generation, with the niche occupied by summer-feeding larvae being broader and different to the autumn one. Measurements of soil temperature confirmed that the short, sheltered foodplants selected by ovipositing females in autumn placed the autumn/spring-feeding generation of larvae in the warmest available microclimates within sites. In late spring, egg-laying females avoided the hottest spots but extended egg-laying into taller, less sheltered (relatively cool) turf where the microclimate was similar to that experienced by autumn/spring-feeding larvae. Using each generations' definition of niche requirement, we analysed surveys of foodplant populations available on 24 UK sites for P. bellargus, and estimated that nearly twice as many plants were available to the summer-feeding larvae compared to those feeding in the autumn. Annual adult population counts match these seasonal differences in site carrying capacity; first generation counts (from autumn-laid eggs) were generally half as abundant as in the second generation, and more variable. These results suggest that the seasonal cycle of niche switches represents an annual (autumn-spring) bottleneck for populations of this butterfly at its northern range margin. Under climate warming we predict that the inter-generational difference in niche availability, carrying capacity and population size will be reduced. We recommend revised management requirements for this threatened species under current and predicted climates in northern Europe.

Conservation of endangered species necessitates a full appreciation of the ecological processes affecting the regulation, limitation, and persistence of populations. These processes are influenced by birth, death, and dispersal events, and characterizing them requires careful accounting of both the deterministic and stochastic processes operating at both local and regional population levels. We combined ecological theory and observations on Allee effects by linking mathematical analysis and the spatial and temporal population dynamics patterns of a highly endangered butterfly, the high brown fritillary, Argynnis adippe. Our theoretical analysis showed that the role of density-dependent feedbacks in the presence of local immigration can influence the strength of Allee effects. Linking this theory to the analysis of the population data revealed strong evidence for both negative density dependence and Allee effects at the landscape or regional scale. These regional dynamics are predicted to be highly influenced by immigration. Using a Bayesian state-space approach, we characterized the local-scale births, deaths, and dispersal effects together with measurement and process uncertainty in the metapopulation. Some form of an Allee effect influenced almost three-quarters of these local populations. Our joint analysis of the deterministic and stochastic dynamics suggests that a conservation priority for this species would be to increase resource availability in currently occupied and, more importantly, in unoccupied sites.

Habitat quality and metapopulation effects are the main hypotheses that currently explain the disproportionate decline of insects in cultivated Holarctic landscapes. The former assumes a degradation in habitat quality for insects within surviving ecosystems, the latter that too few, small or isolated islands of ecosystem remain in landscapes for populations to persist. These hypotheses are often treated as alternatives, and this can lead to serious conflict in the interpretations of conservationists. We present the first empirical demonstration that habitat quality and site isolation are both important determinants of where populations persist in modern landscapes. We described the precise habitat requirements of Melitaea cinxia, Polyommatus bellargus and Thymelicus acteon, and quantified the variation in carrying capacity within each butterfly's niche. We then made detailed surveys to compare the distribution and density of every population of each species with the size, distance apart and quality of their specific habitats in all their potential habitat patches in three UK landscapes. In each case, within-site variation in habitat quality explained which patches supported a species' population two to three times better than site isolation. Site area and occupancy were not correlated in any species. Instead of representing alternative paradigms, habitat quality and spatial effects operate at different hierarchical levels within the same process: habitat quality is the missing third parameter in metapopulation dynamics, contributing more to species persistence, on the basis of these results, than site area or isolation. A reorientation in conservation priorities is recommended.

Summary 1 The effect of weather on the size of British butterfly populations was studied using national weather records and the Butterfly Monitoring Scheme (BMS), a national database that has measured butterfly abundance since 1976. 2 Strong associations between weather and population fluctuations and trends were found in 28 of 31 species studied. The main positive associations were with warm summer (especially June) temperature during the current and previous year, low rainfall in the current year and high rainfall in the previous year. Most bivoltine species benefited from warm June weather in the current year, three spring species and two that overwinter as adults benefited from warm weather in the previous summer, and most species with moist or semi-shaded habitats increased following high rainfall and cooler weather in the previous year. 3 Simple models incorporating weather variables and density effects were constructed for each species using the first 15 years’ population data (1976–90). These fitted the observed data for that period well (median R2 = 70%). Models were less good at predicting changes in abundance over the next 7 years (1991–97), although significant predictive success was obtained. 4 Parameter values of models were then adjusted to incorporate the full 22-year data-run. For the eight species whose models had best predicted population changes or fitted the data well (R2 > 85%), models were run from 1767 to 1997, using historical weather records, to ‘predict’ trends in abundance over the past two centuries. For three species it was possible to compare predicted past trends with contemporary accounts of abundance since 1800. In each case, the match between predictions and these qualitative assessments was good. 5 Models were also used to predict future changes in abundance, using three published scenarios for climate change. Most, but not all, species are predicted to increase in the UK under warmer climates, a few species stayed stable, and only one species – the agricultural pest Pieris brassicae (Cabbage White) – is predicted to decline.

Recent recordings of the stridulations of Myrmica ants revealed that their queens made distinctive sounds from their workers, although the acoustics of queens and workers, respectively, were the same in different species of Myrmica. Queen recordings induced enhanced protective behavior when played to workers in the one species tested. Larvae and pupae of the butterfly genus Maculinea inhabit Myrmica colonies as social parasites, and both stages generate sounds that mimic those of a Myrmica queen, inducing similar superior treatments from workers as their model. We discuss how initial penetration and acceptance as a colony member is achieved by Maculinea through mimicking the species-specific semio-chemicals of their hosts, and how acoustical mimicry is then employed to elevate the parasite's membership of that society towards the highest attainable level in their host's hierarchy. We postulate that, if acoustics is as well developed a means of communication in certain ants as these studies suggest, then others among an estimated 10,000 species of ant social parasite may supplement their well-known use of chemical and tactile mimicry to trick host ants with mimicry of host acoustical systems.

Mean global temperatures have risen this century, and further warming is predicted to continue for the next 50-100 years(1-3) Some migratory species can respond rapidly to yearly climate variation ...

Caterpillars of Maculinea rebeli have two growth strategies for living underground as social parasites of Myrmica ant colonies. Laboratory experiments and field data show that 25% of caterpillars live ten months with ants before pupating, whereas 75% grow slowly, parasitizing their hosts for 22 months. Both types of caterpillar form apparently identical similar-sized pupae. This may be the first description in the animal kingdom of polymorphic growth rates spanning different years within the same population, yet without resulting (as in salmonid fish) in two morphologically distinct adult types with obvious differences in behaviour. We suggest that a balanced polymorphism has evolved in M. rebeli growth rates, representing the most efficient way of exploiting the limited, yet steady, daily supply of food available to cuckoo-feeding parasites of long-lived ant societies. Bet-hedging benefits would also accrue to adult butterflies producing a mixture of annual and biennial offspring. Despite ergonomic and other benefits, partial biennialism is unlikely to evolve unless slow-growing individuals have enhanced survival and can remain attached to their mobile hosts. We show that caterpillars become so closely protected by, and integrated with, their host colonies that slow growers experience no greater mortality over two years than fast growers over one, and are transported in preference to the ants' own larvae when the host colony moves nest site.

The lycaenid butterfly, Maculinea rebeli, and its specialist parasitoid, Ichneumon eumerus, live in small, closed populations. Given the threatened status of the butterfly, it is reasonable to assume that its specialist parasitoid is even more vulnerable to local extinction than the butterfly host. Based on a mechanistic model recently developed for the tightly-woven community surrounding M. rebeli at a site in the Spanish Pyrenees, we investigate how the removal of habitat, and more particularly, specific habitat promoting the persistence of the butterfly, affects the population persistence of the parasitoid. Because of the relatively small impact of the parasitoid on the butterfly population in the Spanish Pyrenees, guidelines for conserving the parasitoid are only slightly more restrictive than those for its host. It is argued that at sites of more marginal quality for the butterfly than the reference site, achieving the dual aims of conserving both species will be more problematic. © Rapid Science Ltd. 1998

In recent spatial models describing interactions among a myrmecophilous butterfly Maculinea rebeli , a gentian Gentiana cruciata and two competing species of Myrmica ant, we predicted that apparent competition should exist between gentians (the food of young M. rebeli caterpillars) and Myrmica schencki , which supports M. rebeli in its final instar. Here we extend and quantify model predictions about the nature of this phenomenon, and relate them to ecological theory. We predict that: (i) Within sites supporting the butterfly, fewer M. schencki colonies occur in sub-areas containing gentians than in identical habitat lacking this plant. (ii) Where G. cruciata and M. schencki do co-exist, the ant colonies will be less than half the size of those living > 1.5 m from gentians; (iii) The turnover of M. schencki colonies will be much greater than that of other Myrmica species in nest sites situated within 1.5 m of a gentian. All three predictions were supported in the field on 3–6 sites in two mountain ranges, although the exact strength of the apparent competition differed from some model predictions. Field data were also consistent with predictions about apparent mutualisms between gentians and other ants. We suggest that apparent competition is likely to arise in any system in which a specialist enemy feeds sequentially on two or more species during its life-cycle, as occurs in many true parasite-host interactions. We also predict that more complex patterns involving other Myrmica species and G. cruciata occur in our system, with apparent competition existing between them in some sub-areas of a site being balanced by apparent mutualism between them in other sub-areas.

1. Published laboratory work suggests that Aglais urticae may be affected adversely by drought, as the larvae thrive on actively growing plants with high leaf water and nitrogen. 2. The weekly counts from the Butterfly Monitoring Scheme were used to test the hypothesis of an association between changes in abundance and drought in field data. 3. The analysis supported the hypothesis; breeding success of the summer generation from 1976 to 1995 was greater when the early summer weather was cool and wet than when it was warm and dry.

Metapopulation studies of single species have shown that the size and spatial arrangement of patches of assumed uniformly 'suitable' habitat can influence their population dynamics and persistence. We investigated whether variation in the spatial arrangement of 'suitable' habitat of varied quality within a single site can affect the abundance and persistence of interacting species. We accomplished this by extending a field-based spatial simulation model of four interacting species at two trophic levels (an endangered butterfly, its larval food-plant, and two ants). The habitat on sites with the same average and range of qualities was rearranged to give varying degrees of local spatial heterogeneity or 'site ruggedness'. We found that the ant species that acts as host to the butterfly caterpillars decreased with site ruggedness. The impact on the butterfly was more substantial: it often failed to persist on very rugged sites. Despite being free-ranging over the whole area, the butterfly's persistence depends on the arrangement of habitat quality at a finer spatial scale, due to its interactions with species possessing narrower habitat niches and more localized dispersal. Ruggedness also influenced the rate of recovery of the host ant, and hence community structure, for more than a century following the butterfly's extinction.

We examine a spatially explicit ‘case m odel’ for the interaction between the lycaenid butterfly, Maculinea rebeli , and its specialist parasitoid, Ichneumon eumerus . This butterfly lives in small, closed populations, rarely numbering over a few thousand individuals, and the parasitoid is found at only a small subset of butterfly-harbouring sites. We explore how parasitoid searching intensity and behaviour, and host refuges from parasitism affect the dynamics of the host-parasitoid couple. In the absence of explicit host refuges, the parasitoid persists only for a very restricted range of search rates and searching behaviours. Absolute refuges to parasitism, modelled as a cue-threshold phenomenon in the elicitation of intensive search for the host, expand the persistence conditions. We link these results to the more general problem of what inferences can be draw n concerning the association between population-level variation in the distribution of parasitism and the population dynamics of the system. The parasitoid’s persistence depends im portantly on heterogeneity in the vulnerability of the host caterpillars to encounter with parasitoids. Although the host’s persistence is also enhanced by such heterogeneity, it is actually intraspecific competition within ant nests that dominates host dynamics. Deductions of the stabilizing power of parasitoids from measures of spatial heterogeneity in parasitism will be spurious without information about the respective density-dependent influences of the parasitoid and other limitation factors affecting the host.

Butterflies are important flagship taxa for invertebrate conservation. Recent developments emphasizing species and habitat management based on sound ecological understanding exemplify progress in this emerging science. Studies in many countries show the complexity of management needs for single species, and examples of management and recovery plans demonstrate the worth of this approach. By contrast, in many tropical regions, where butterfly faunas are more diverse than in temperate zones and the resources for practical conservation are restricted, the major emphasis is on protection of habitats to safeguard relatively poorly documented assemblages, and on conservation measures that benefit local people. Aspects of butterfly ecology are discussed in relation to sound management of species and faunas, and selected examples from Europe, North America, and elsewhere exemplify increasing global interest in butterfly conservation.

An emerging problem in conservation is whether listed morpho-species with broad distributions, yet specialized lifestyles, consist of more than one cryptic species or functionally distinct forms that have different ecological requirements. We describe extreme regional divergence within an iconic endangered butterfly, whose socially parasitic young stages use non-visual, non-tactile cues to infiltrate and supplant the brood in ant societies. Although indistinguishable morphologically or when using current mitochondrial and nuclear sequence-, or microsatellite data, Maculinea rebeli from Spain and southeast Poland exploit different Myrmica ant species and experience 100 per cent mortality with each other's hosts. This reflects major differences in the hydrocarbons synthesized from each region by the larvae, which so closely mimic the recognition profiles of their respective hosts that nurse ants afford each parasite a social status above that of their own kin larvae. The two host ants occupy separate niches within grassland; thus, conservation management must differ in each region. Similar cryptic differentiation may be common, yet equally hard to detect, among the approximately 10 000 unstudied morpho-species of social parasite that are estimated to exist, many of which are Red Data Book listed.

Populations at the high latitude edge of species' geographical ranges are thought to show larger interannual population fluctuations, with subsequent higher local extinction risk, than those within the 'core' climatic range. As climate envelopes shift northward under climate warming, however, we would expect populations to show dampened variability. We test this hypothesis using annual abundance indices from 19 butterfly species across 79 British monitoring sites between 1976 and 2009, a period of climatic warming. We found that populations in the latter (warmer) half of the recording period show reduced interannual population variability. Species with more southerly European distributions showed the greatest dampening in population variability over time. Our results suggest that increases in population variability occur towards climatic range boundaries. British sites, previously existing at the margins of suitable climate space, now appear to fall closer to the core climatic range for many butterfly species. © 2012 Blackwell Publishing Ltd.

Twenty-nine butterfly species are listed on the Annexes of the Habitats Directive. To assist everyone who wants or needs to take action for one of these species, we compiled an overview of the habitat requirements and ecology of each species, as well as information on their conservation status in Europe. This was taken from the recent Red List and their main biogeographical regions (taken from the first reporting on Article 17 of the Directive). Most important are the Dos and Don`ts, which summarize in a few bullet points what to do and what to avoid in order to protect and conserve these butterflies and their habitats.

Data from a national butterfly monitoring scheme were analysed to test the theory that animal populations are more variable towards the edges of species ranges Nine of the 24 species tested fluctuated with significantly greater amplitude nearer their northern limits, providing the first clear evidence of this phenomenon among ectotherms With some species, the pattern of fluctuations also varied across ranges with populations increasing and decreasing more gradually, and perhaps cyclically, over several generations in the north

The ecology of the declining butterfly Aricia agestis was studied in southern England by measuring oviposition preferences, and from population estimates and habitat analyses of colonies on seven sites. The adults live in small, predominantly closed populations, although movement is not as restricted as in most other lycaenid butterflies studied. Butterfly collectors pose little threat to this species; population size is instead restricted by the precise ecological requirements of the egg site, and hence the larval stage. A. agestis chooses ‘lush’, sheltered growths of the larval foodplant, Helianthemum chamaecistus . The organic nitrogen content and mesophyll thickness of plants selected for oviposition on study sites were significantly higher than in randomly selected plants. Structural features of the foodplant and its surroundings were less important than for other lycaenids; although the presence of bare ground influenced oviposition, turf height — at least at the study sites—did not. A survey of seven sites showed no correlation between the densities of A. agestis and H. chamaecistus , but there was a strong correlation between butterfly density and the number of the lush foodplants that were growing in the form chosen for oviposition. Priorities for the management of sites are suggested.

We found several rare UK butterflies to be restricted to relatively large and non-isolated habitat patches, while small patches and those that are isolated from population sources remain vacant. These patterns of occurrence are generated by the dynamic processes of local extinction and colonization. Habitat patches act as terrestrial archipelagos in which long-term population persistence, and hence effective long-term conservation, rely on networks of suitable habitats, sufficiently close to allow natural dispersal.

Large blue butterflies are notable for their rarity and ability to dupe ants, and they are endangered. A genetic reconstruction of how social parasitism evolved among them will overturn conservation priorities.

Five of the world’s six species of Maculinea butterfly live in Europe. They are among the few insects for which specific conservation measures have been taken, and are regarded as ‘flagship’ species by many Western conservationists (Anon., 1993a). Thus Maculinea butterflies are regularly used for logos and on stamps (Anon., 1981, 1993b), have been the subject of numerous radio and television broadcasts and have frequently featured in magazines as diverse as the National Geographic and The Economist and in newspapers ranging from the European to the Sun.

Caterpillars of the butterfly, Maculinea rebeli, feed sequentially in flower-buds of Gentiana cruciata and in nests of Myrmica schencki ants, with which they have a sort of'cuckoo bird' relationship. Ants feed them in preference to their own larvae, reducing the production of new workers and hence the colony size the following year. Other Myrmica compete with M. schencki for nest-sites. They adopt caterpillars with equal facility, but fail to rear them to maturity and are consequently less damaged. Using a mathematical model we explore how species interactions can influence the populations of the butterfly, M. schencki, and other Myrmica species. The model assumes a 1 ha square of 900 cells with a fixed population of gentians

The five European species of Maculinea butterflies are among the most en-dangered invertebrates in the world. To attain a better understanding of the mechanisms which are most influential to their population dynamics, we develop a mathematical population model for one of these species, Maculinea rebeli, based on its dependence on two sequential resources, the cross-leaved gentian, Gentiana cruciata, and a red ant, Myrmica schencki. One of the main objects of this modelling study is to raise questions about the ecology and conservation of this rare and fascinating butterfly

An extensive survey was made of known and potential sites of the heath fritillary butterfly Melllicta athalia Rott. in Great Britain in 1980. The size of every colony found was measured and information obtained on its habitat preferences and larval foodplants. Details of all the sites that still support this butterfly are summarised and its habitat requirements are assessed. The survey confirmed that the heath fritillary is probably the most endangered resident butterfly in Britain. It has declined severely in recent years and is now restricted to five sites in SW England and to three woodland blocks in E Kent. Thirty-one colonies were discovered (6 in the SW, 25 in Kent), but 24 of these contained fewer than 200 adults on the peak day. Moreover, several occurred close to larger populations and may only be offshoots that would not be viable on their own. The heath fritillary has different habitat requirements in SW England and Kent, although in both regions it needs sunny sheltered woodland that is at an early stage of succession or regeneration. Such habitat is ephemeral and must be generated continuously within fairly small areas if it is to be utilised, for the butterfly rarely flies long distances. Nearly all documented extinctions have been caused by a loss of suitable habitat from the locality, for this is only occasionally created by most modern forms of silviculture. In Kent, the heath fritillary survives mainly in the ever-decreasing areas where traditional coppicing has continued, but the future of this practice is now in doubt. Few colonies survive in SW England, although some are now being managed specifically to safeguard the butterfly.

In 1979 the Nature Conservancy Council revealed that the large blue butterfly Maculinea arion was probably extinct in Britain, despite much research and valiant efforts to save it. The author, a member of the Institute of Terrestrial Ecology, who since 1972 has been engaged full time on the research and conservation work for the butterfly, tells the story as it is now known.

The importance of early-successional stages for the conservation of threatened butterflies of calcareous grassland, and reasons for their decline, are outlined. The opportunity to re-establish chalk on a site made available through construction of a motorway (the Bar End to Compton section of the M3, Hampshire) is described. The characteristics of the site are compared with present-day and historical conditions on the adjacent St Catherine's Hill Site of Special Scientific Interest. Details of proposals to modify the topography of the site by ecological engineering are given. This modification is based upon a detailed knowledge of the ecological requirements of a range of scarce butterfly species, microclimatic observations and an assessment of available resources for re-vegetating the site. The reason for the failure to implement the proposals are discussed. It is suggested that conservationists need to give greater emphasis to dynamic aspects of conservation and re-creation of early-successional communities.

(1) A survey was made of all British colonies of Hesperia comma, which revealed that it had declined to about forty-nine populations, most of which were small. (2) Adult H. comma proved to be very particular when egg-laying. They preferred small Festuca ovina plants that were largely surrounded by bare ground or scree, and which also grew in sheltered sunspots. Most F. ovina growing on most sites were rejected as unsuitable, and the adult population density of H. comma was correlated with how closely the sward approached the ideal structure for egg-laying. (3) Most sites that had lost H. comma still contained abundant F. ovina, but were too overgrown to be suitable for breeding. Most extinctions of H. comma occurred during a twenty-year period, when many unfertilized downs in Britain became overgrown after rabbits were killed by myxomatosis. (4) The habitat on several former sites has improved for H. comma since the late 1970s, due to a recovery by rabbits and some sheep stocking on abandoned downs. To date, H. comma has only spread to re-occupy sites that were within 4 km of existing colonies. The natural recolonization of other sites may take decades or centuries. (5) Conservationists could dramatically improve the status of H. comma by making artificial introductions to unoccupied sites. A high proportion of the existing colonies are already on nature reserves, but one-quarter of 'protected' populations had become extinct by 1982, due to inadequate grazing.